Image processing apparatus and method for generating an image signal for gradation

Abstract

An image processing apparatus includes a receiving section, an edge detection section and a screen processing section. The receiving section receives image information. The edge detection section detects an edge area from the image information received by the receiving section. The screen processing section performs a screen process, which is based on area coverage modulation, for the image information on a basis of the detection result by the edge detection section. The screen processing section performs a screen process for the edge area detected by the edge detection section with (i) a screen angle, which is equal to that of a screen process performed for a non-edge area other than the edge area, and (ii) a number of lines per inch, which is an integer multiple of that of the screen process performed for the non-edge area.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based on and claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2006-329284 filed on Dec. 6, 2006.BACKGROUND[0002]1. Technical Field[0003]The invention relates to an image processing apparatus and an image processing method for generating an image signal representing gradation using an area coverage modulation method.[0004]2. Related Art[0005]An image formation apparatus such as a copier or a printer using electrophotography, an ink jet system, etc., performs for input image information a screen process of artificially reproducing a halftone with binary values representing presence or absence of a drawing dot, and outputs the result by means of an output device.[0006]A document generated by such an image formation apparatus includes various objects from the viewpoint of the image quality, such as an image of a photo, etc., graphics of gradation, patch, etc., and text, a line, etc.,[0007]The numbe...

AI Technical Summary

Benefits of technology

[0012]According to an aspect of the invention, an image processing apparatus includes a receiving section, an edge detection section and a screen processing section. The receiving section receives image information. The edge detection section detects an edge area from the image information received by the receiving section. The screen processing section performs a screen process, which is based on area coverage modulation, for the image information on a basis of the detection result by the edge detection section. The screen processing section performs a screen process for the edge area detected by the edge detection section with (i) a screen angle, which is equal to that of a screen process performed for a non-edge area other than the edge area, and (ii) a number of lines per inch, which is an integer multiple of that of the screen process performed for the non-edge area.

Problems solved by technology

However, 170 to 230 lines per inch are often used because the gradation property and graininess are degraded due to the responsiveness of a marking engine if the number of lines per inch is high and because a screen structure is seen or texture is lost if the number of lines per inch is low.

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